Electric melting furnace



I 1,477,821 A. w. GREGG ELECTRIC IELTING I'URIAGE Filed July 16 1921 2 Sheets-Sheet 1 Dec. 18,1923.

WE W G 1. r 399 19 Mun/u 1 y.

Patented Dec. 18, '1923.

UNITED STATES ALFRED GREGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO WHITIN G CORPORATION, OF

HARVEY, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRIC MELTIN G FURNACE.

Application filed July 16, 1921. Serial No. 485,175.

To all whom it may concern:

Be it known that I, ALFRED W. GREGG,

a citizen of the United States, residing at Chicago, in the county of Cook and State 6 of Illinois, have invented a certain new and useful Improvement in Electric Melting Furnaces, of which the following is a specification.

This invention relates to electric melting furnaces for liquefying metal by the aid of an electric arc. The object of the invention is to provide a furnace in which the metal is heated, liquefied and refined by radiant heat and conduction as distinguished from current passing thru the metal itself. A further object is to provide a furnace of this type of such a construction that a continuous circulation of molten metal is produced, thus insuring a more uniform physical and chemical mixture and a more uniform temperature in the molten product than is possible with devices heretofore in use.

The invent-ion consists in a device capable of attaining the foregoing objects which can be easily and cheaply made and installed, which is satisfactor in use and is not liable to get out of order, and also in many features and details of construction which will be hereafter more fully set forth in the specification and claims.

Referring to the drawings in which like numerals designate the: same parts thruout the several views:

Figure 1 is a side elevation in section of a furnace illustrating this invention in its preferred form.

Figure 2 is a reduced size plan view partially in section of the structure, Figure 1.

Figure 3 is a sectional view of a device taken on the line 33, Figure 2.

The furnace includes the box like receptacle 10 of any convenient horizontal cross section supported on trunnions 12 journaled in upright standards 14 conventionally shown as secured to the floor by bolts 16. This box 10 initially open at the top is nor mally closed by an arched cover 18 suitably fitted into a cover retaining frame 20 bordering the top of the box 10 to 'form inside the box a closed melting chamber 22 adapted to receive metal to be melted thru charging door 24, in one end of the box or furnace and to discharge olten metal through a spout 26 provided in the opposite end.

The bottom or hearth 28 of furnace chamber 22 consists of a relatively thick coating of gannister or other refractory material which also extends vertically up the insides and corners of the vertical walls of the chamber in protecting walls29. This gannister is so moulded at the corners that the horizontal cross section of chamber 22 is approximately oval as shown. The refractory material may be acid or basic in character depending on the work of the furnace. Formed in the center of this thick main hearth 28 of refractory material is an is land 30 of the same material. In the par ticular case here illustrated this island is of elongated or oval form as distinguished from circular or triangular and is in general concentric with the wall of chamber 22 so that molten metal can flow completely around it. The electrodes 32, 34, and 36 enter the chamber 22 thru the roof 18 and closely approach a bed of carbon 38 embedded in a carborundum trough or support 40 carried by the island 30. These electrodes lie in the longer axis of island 30, viz, that which extends thru spout 26. In the particular case here illustrated these electrodes 32, 34, and 36 are connected to a three-phase electric current supply mechanism well understood in the art, and therefore not shown in detail, supp-lying current into the furnace, The circuit is completed thru the broken carbon 38 supported in the trough 30. This makes intensely hot mufiied arcs at the points of contact 42, 44, and 46, where the electrodes approach carbon 38. The upper surface of the body of refractory material 28 being the floor of the furnace chamber 22 is formed in an inclined or dished surface 48 inclined downward, all about the island 30 and entirely across all portions of the furnace bottom toward low points 50 immediately adjacent to the base of the island 30. When the heat from the are points 42, 44, and 46 is reflected upward against the curved lower surface 52 of the roof 18 and is by it reflected downward onto the metal 54 in the furnace around the island 30, the hottest part of this metal isnecessarily the portion .closest to the island 30 and closest to the arcs 42, 44, and 46 While cooler portions are found adjacent to the walls 29. Therefore, in accordance with the suitable sort of a receptacle. Thereafter, the" well known physical laws, the cooler metal adjacent to the walls 29 tends to flow down inclined surface 48 to the points 50 and said hottest metal above the points 50 flows outward from the island 30 toward the walls 29, whereupon the metal at the bottom of the points 50 rises to the top into the intense heated area described. There is, therefore, in theory and as is demonstrated in practice a continuous circulation of metal in the paths described.

Wholly apart from the foregoing there being three arcs at the points 42, 44, and 46 adjacent to the side walls at the ends of the shorter diameter of the. oval melting chamber 22, metal at this shorter diameter is heated hotter than is the metal at the extreme ends of the longer diameter of the heating chamber. There being such a difference in temperature in the metal, the hotter metal tends to flow from the shorter diameter of chamber 22 (the one which includes the trunnions 12) around to the longer diameter, (the one which includes the spout 26) with a resulting further mixing of the molten metal.

In the operation of the device the cover 18 is removed whenever-it becomes necessary to renew the lining. The metal to be melted is placed in the chamber 22 about the island 30, after which the furnace is closed and the current is turned on, thereby producing the intensely hot arcs at the points 42,

44, and 46. The heat from these arcs is first reflected in the manner described, onto the metal 54, melting it first partially, then completely. As the metal bath melts, it circulates in the manner described and for the reasons described with the result that a quantity of well mixed molten metal 6f substantially uniform temperature is produced. When the metal is in proper condition for tapping the furnace can be tilted on its trunnions 12 to allow the metal to flow from the spout 26 into any furnace is recharged through doors 24 and the operation repeated.

The device heretofore described is also of such a shape that by chipping out the island 30 and the parts carried by 1t, a direct arc nae/near furnace, in which the current is passed thru the metal itself, is easily produced.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Tn a device of the class described, a furnace chamber enclosing a hearth, sloping continuously downward from the side walls of the chamber toward its center, a central island in the hearth, and means for creating an electric are on the island without passing electric current through material to be melted on the hearth.

2. In a device of the class described, a furnace chamber enclosing a hearth sloping continuously downward from the side walls of the chamber toward its center, a central island in the hearth, means for creating an electric are on the island without passing electric current through material to be melted on the hearth, and an arched roof to the furnace chamber reflecting heat rays from the electric arc onto the hearth.

3. In a device of the class described, an oval furnace chamber enclosing a hearth sloping continuously downward from the side walls of the chamber toward its center, an oval central island in the hearth, and means for creating a plurality of electric arcs along the longer axis of the island without passing electric current through 1naterial to be melted on the hearth.

4. In a device of the class described, an oval furnace chamber enclosing a hearth sloping continuously downward from the side walls of the chamber toward its center, an oval central island in the hearth, means for creating a plurality of electric arcs along the longer axis of the island without passing electric current through material to be melted on the hearth, and an arched roof to the furnace chamber reflecting heat rays from the electric arc onto the hearth.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

ALFRED W. canes.

Witnesses: J. S. TOWNSEND, HARRY W. BAKER. 

